In a stator of an ac generator for a vehicle, an electrical insulating member is generally used to insulate a stator winding including electric conductors from a stator core. When the electric conductors are bent in a circumferential direction at an axial outside of the stator core to form the stator winding, an end of the insulating member is likely to be expanded and torn. To reduce such breakage of the insulating member, it is proposed to form slits at the end of the insulating member, for example, in Unexamined Japanese Patent Publication No. JP-A-2001-178057.
Since the slit is formed at the part of the insulating member, the end of the insulating member is not forcibly entirely expanded even when the electric conductors, which are arranged adjacent in a radial direction in a slot of the stator core, are bent in the circumferentially opposite direction. Because the insulating member is expanded only at a necessary portion, it is less likely that the end of the insulating member will be torn.
However, because a distance between the electric conductor and the stator core is reduced at the slit, the electric conductor and the stator core are likely to be short-circuited. Therefore, it is difficult to sufficiently maintain the electrical insulation between the electric conductors and the stator core. To improve the electrical insulation, it is conceived to shorten the slit. In this case, however, because the end of the slit is located axial outside of the axial end surface of the stator core, the insulating member will be easily torn at the end of the slit while bending the electric conductors. The short circuit between the electric conductors and the stator core is likely to cause abnormal power generation, resulting in deterioration of an environmental resistance.